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參數(shù)資料
| 型號： | MAX5913 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | +48V Quad Hot-Swap Controllers For Power-Over-LAN |
| 中文描述： | +48V、四路、熱插拔控制器，用于LAN供電 |
| 文件頁數(shù)： | 16/20頁 |
| 文件大?。?/td> | 827K |
| 代理商： | MAX5913 |
M
+48V Quad Hot-Swap Controllers For
Power-Over-LAN
16
______________________________________________________________________________________
threshold current, the open-circuit detector turns off the
switch after a 25.6ms delay,
FAULT
goes low and the
Port-OC flag is set for that switch. To clear the switch
latched-off condition,
FAULT
and Port-OC flags drive
the corresponding ON input low.
Overcurrent Faults
When an on switch current exceeds the current-limit
threshold, foldback circuitry activates and regulates the
switch current. When current limit lasts for longer than
t
O
, the switch latches off. The Power-OK status flag is
set low, and the
FAULT
flag is set. If auto-retry is
enabled, the switch remains off for a period t
OFF
. If
auto-retry is disabled, the switch remains latched off,
and
FAULT
is low. Reset the latch and
FAULT
by dri-
ving corresponding ON_ low.
Applications Information
Considerations for circuit design include output capaci-
tor requirements, current-limit requirements, setting the
maximum on-time in current limit, and choosing a suit-
able MOSFET and on-time duty cycle in auto-retry.
Output Capacitor Requirements
The load capacitor requirements should be determined
first, as this affects the required startup.
Current-Limit Requirements
(Choosing R
SENSE
)
The current limit should be set to at least 20% higher
than the expected full load current. If current limit is
also used to control startup current, then set this limit
high enough so that the output voltage can rise and
settle before t
O
elapses (see
Setting t
O
section below).
Setting t
O
(Choosing R
RTIM
)
Choose the t
O
time by connecting a 2k
to 40k
resistor
from RTIM to DGND. The minimum 6.4ms t
O
is set with
R
RTIM
= 2k
. The maximum 128ms t
O
is set with R
RTIM
= 40k
set according to the following equation:
t
O
= (R
RTIM
/ 2k
) (6.4ms).
t
O
should be chosen appropriately, depending on the
startup condition. There are two cases:
1) For startup without current limit, when
the startup current does not reach the maximum cur-
rent-limit threshold and t
O
will not activate during
startup condition. In this case, set t
O
to a small
value, but large enough to allow the switch to remain
on during large output load-current transients. The
smaller the t
O
, the faster the MAX5913/MAX5914
turn off the external FET in case of output overload
or short-circuit condition.
2) For startup with current limit, when
which is expected when
is large, t
O
must be set to be long enough to allow the
output voltage to rise and settle before t
O
elapses. In
this case, t
O
must satisfy the following equation:
where V
CC
is the input voltage and given that I
L
< I
LIM
.
Choosing Power MOSFET
The FET must withstand a short-circuit condition where
its power dissipation is P
DISS
= V
CC
I
LIM
. The FET
must have sufficient thermal capacitance to prevent
thermal heating damage during the t
O
time.
Choose Duty Cycle (setting DC)
The duty cycle can be adjusted to allow time for heat to
dissipate between t
O
cycles, allowing use of smaller
MOSFETs with lower thermal capacitance. For smaller
duty cycle, a smaller FET is sufficient. See Table 2 for
setting the duty cycle.
The auto-retry off-time should not be too long to keep
system wait time during retry period to a reasonable
value. For example, when t
O
is set to 128ms and duty
cycle is set to 1%, the retry time is 99
128ms = 12.7s.
Application Circuits
In a typical LAN system there are two ways to deliver
power over the LAN cable. Power can be supplied to
the unused cable pairs, or power can be supplied over
the signal pairs (Figures 9 and 10).
t
C
I
I
C
V
I
V
I
O
L
MAX
L
L
CC
MAX
L
=
+
18
2
3
18
C
C
L
GATE
I I
C
C
I
V
R
GATE
L
GATE
L
SC
SENSE
+
≥
I I
C
C
I
V
R
GATE
L
GATE
L
SC
SENSE
+
<
相關PDF資料 |
PDF描述 |
|---|---|
| MAX5913EMH | +48V Quad Hot-Swap Controllers For Power-Over-LAN |
| MAX5914EMH | +48V Quad Hot-Swap Controllers For Power-Over-LAN |
| MAX6018 | ER 9C 9#16 SKT PLUG |
| MAX6018AEUR12 | Circular Connector; No. of Contacts:3; Series:; Body Material:Aluminum Alloy; Connecting Termination:Solder; Connector Shell Size:22; Circular Contact Gender:Pin; Circular Shell Style:Straight Plug; Insert Arrangement:22-21 RoHS Compliant: No |
| MAX6018AEUR12-T | ER 4C 4#8 PIN PLUG |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX5913AEMH | 功能描述:熱插拔功率分布 RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MAX5913AEMH+ | 功能描述:熱插拔功率分布 48V Hot-Swap Controller RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MAX5913AEMH+D | 制造商:Maxim Integrated Products 功能描述:HOT SWAP CNTRLR 44MQFP - Rail/Tube |
| MAX5913AEMH+T | 功能描述:熱插拔功率分布 48V Hot-Swap Controller RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MAX5913AEMH+TD | 制造商:Maxim Integrated Products 功能描述:HOT SWAP CNTRLR 44MQFP - Tape and Reel |
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